Arterial stiffness as a cause of cognitive decline and dementia: a systematic review and meta-analysis

BOLD cardiorespiratory pulsatility in the brain: from noise to signal of interest

Functional magnetic resonance imaging (fMRI) based on the Blood Oxygen Level Dependent (BOLD) contrast has been extensively used to map brain activity and connectivity in health and disease. Standard fMRI preprocessing includes different steps to remove confounds unrelated to neuronal activity. First, this narrative review explores how signal fluctuations due to cardiac and respiratory activity, usually considered as "physiological noise" and regressed out from fMRI time series. However, these signal components bear useful information about some mechanisms of brain functioning (e.g., glymphatic clearance) or cerebrovascular compliance in response to arterial pressure waves. Aging and chronic diseases can cause stiffening of the aorta and other main arteries, with a reduced dampening effect resulting in greater transmission of pressure impulses to the brain. Importantly, the continuous hammering of cardiac pulsations can produce local alterations of the mechanical properties of the small cerebral vessels, with a progressive deterioration that ultimately affects neuronal functionality. Second, the review emphasizes how fMRI can study the brain patterns most affected by cardiac pulsations in health and disease with high spatiotemporal resolution, offering the opportunity to identify much more specific risk markers than systemic factors based on measurements of the vascular compliance of large arteries or other global risk factors. In this regard, modern fast fMRI acquisition techniques allow a better characterization of these pulsatile signal components due to reduced aliasing effects, turning what has been traditionally considered as noise in a signal of interest that can be used to develop novel non-invasive biomarkers in different clinical contexts.

Aortic Characteristic Impedance and Suspected Mild Cognitive Impairment in a Community-Based Healthy Population

BACKGROUND

Aging of the proximal aorta can lead to increased pressure and flow pulsatility in the cerebral microcirculation, which may cause cognitive impairment. This study investigated the association between aortic characteristic impedance (Zc), an indicator of regional stiffness of the proximal aorta, and suspected mild cognitive impairment (MCI), compared with carotid-femoral pulse wave velocity (CFPWV).

METHODS AND RESULTS

A total of 1461 healthy community residents (46.4% men; age range, 35-96 years [mean±SD, 59.9±11.8 years]) without a history of cardiovascular events or stroke were included in the study. Zc was estimated using applanation tonometry and echocardiography. Cognitive function was assessed using the Mini-Mental State Examination. Education-adjusted cut points were used to define suspected MCI. Subjects with suspected MCI (n=493 [33.7%]) had significantly higher Zc and CFPWV than those without. In multivariable analysis, both Zc and CFPWV were inversely associated with Mini-Mental State Examination score. Zc (odds ratio per 1 SD, 1.22 [95% CI, 1.09-1.37] and CFPWV (odds ratio per 1 SD, 1.18 [95% CI, 1.01-1.38]) was also significantly associated with suspected MCI, after adjusting for age, sex, education level, mean arterial pressure, hypertension, diabetes, low-density lipoprotein cholesterol, and smoking status. In joint analysis, Zc was significantly associated with suspected MCI, but CFPWV was not. In the age subgroups of <50 years and 50 to 70 years, only Zc was significantly associated with suspected MCI.

CONCLUSIONS

This study found that Zc was significantly associated with Mini-Mental State Examination score and suspected MCI, especially in younger and middle-aged adults. These findings suggest that Zc may be a useful biomarker for identifying individuals at risk for MCI.

Arterial stiffness and physical fitness on cognitive function in community-dwelling middle-aged and older adults

PURPOSE

This study examined whether decline in cognitive function is related to arterial stiffness and reduction in physical fitness in middle-aged and older adults.

METHODS

A total of 1554 healthy middle-aged and older adults participated in this study. The trail making test parts-A (TMT-A) and B (TMT-B), brachial-ankle pulse wave velocity (baPWV), grip strength, the 30-s chair stand (CS-30) test, the 6-min walk (6MW) test, the 8-foot up-and-go (8UG) test and gait assessment were performed. Participants were classified into a middle-aged group (40-64 years; mean, 50.4 ± 0.2 years) or an older group (≥ 65 years; mean, 73.1 ± 0.5 years), as well as into three cognition (COG) groups (high, moderate, and low) based on median TMT-A and -B scores (high scores on both, either, or neither TMT-A and -B, respectively).

RESULTS

The results revealed that baPWV was significantly lower in the high-than in the moderate- and low-COG groups in both middle-aged and older adults (P < 0.05). In addition, except for a few parameters (e.g., 6MW test in middle-aged adults), physical fitness was significantly higher in the high-than in the moderate- and low-COG groups in both middle-aged and older adults (P < 0.05). Multivariate regression analysis revealed that baPWV (P < 0.05) and some physical fitness indicators (grip strength, CS-30, and 8UG) were significantly independently associated with both TMT-A and -B in the middle-aged and older groups (P < 0.05).

CONCLUSION

These results suggest that increased arterial stiffness and reduced physical fitness are associated with impaired cognitive function in middle-aged and older adults.

Vascular cognitive impairment - Past, present, and future challenges

Vascular cognitive impairment (VCI) is a lifelong process encompassing a broad spectrum of cognitive disorders, ranging from subtle or mild deficits to prodromal and fully developed dementia, originating from cerebrovascular lesions such as large and small vessel disease. Genetic predisposition and environmental exposure to risk factors such as unhealthy lifestyles, hypertension, cardiovascular disease, and metabolic disorders will synergistically interact, yielding biochemical and structural brain changes, ultimately culminating in VCI. However, little is known about the pathological processes underlying VCI and the temporal dynamics between risk factors and disease mechanisms (biochemical and structural brain changes). This narrative review aims to provide an evidence-based summary of the link between individual vascular risk/disorders and cognitive dysfunction and the potential structural and biochemical pathophysiological processes. We also discuss some key challenges for future research on VCI. There is a need to shift from individual risk factors/disorders to comorbid vascular burden, identifying and integrating imaging and fluid biomarkers, implementing a life-course approach, considering possible neuroprotective influences of positive life exposures, and addressing biological sex at birth and gender differences. Finally, this review highlights the need for future researchers to leverage and integrate multidimensional data to advance our understanding of the mechanisms and pathophysiology of VCI.

Pyridoxamine treatment ameliorates large artery stiffening and cerebral artery endothelial dysfunction in old mice

Age-related increases in large artery stiffness are associated with cerebrovascular dysfunction and cognitive impairment. Pyridoxamine treatment prevents large artery stiffening with advancing age, but the effects of pyridoxamine treatment on the cerebral vasculature or cognition is unknown. The purpose of this study was to investigate the effects of pyridoxamine on blood pressure, large artery stiffness, cerebral artery function, and cognitive function in old mice. Old male C57BL/6 mice consumed either pyridoxamine (2 g/L) or vehicle control in drinking water for ∼7.5 months and were compared with young male C57BL/6 mice. From pre- to post-treatment, systolic blood pressure increased in old control mice, but was maintained in pyridoxamine treated mice. Large artery stiffness decreased in pyridoxamine-treated mice but was unaffected in control mice. Pyridoxamine-treated mice had greater cerebral artery endothelium-dependent dilation compared with old control mice, and not different from young mice. Old control mice had impaired cognitive function; however, pyridoxamine only partially preserved cognitive function in old mice. In summary, pyridoxamine treatment in old mice prevented age-related increases in blood pressure, reduced large artery stiffness, preserved cerebral artery endothelial function, and partially preserved cognitive function. Taken together, these results suggest that pyridoxamine treatment may limit vascular aging.

Diastolic Blood Pressure and Cognitive Functioning: Differences by Systolic Blood Pressure Among US Adults

BACKGROUND

The role of diastolic blood pressure (DBP) with cognitive functioning is under-explored in relation to levels of systolic blood pressure (SBP).

METHODS

We studied 5466 participants from the National Health and Nutrition Examination Survey. Blood pressure was measured 3 times manually with a standardized sphygmomanometer and averaged. Cognitive functioning was measured using the digit symbol substitution test (DSST).

RESULTS

Participants were 60 years or older, 55% female, and 81% non-Hispanic White. Most participants had a DBP between 70 to <80 mmHg (33.7%), between 60 to <70 mmHg (29.3%), or <60 mmHg (18.8%). From multivariable linear regression analyses, each 5 mmHg increment of DBP was associated with significantly higher DSST scores among individuals with SBP <120 only (ß: 0.56, 95% CI: 0.09, 1.03).

CONCLUSIONS

Among older US adults, at non-elevated levels of SBP, higher DBP is associated with better cognitive performance.

Association of resting heart rate with cognitive decline and dementia in older adults: A population-based cohort study

INTRODUCTION

Resting heart rate (RHR) predicts future risk for cardiovascular disease (CVD). However, longitudinal studies investigating the relationship of RHR with cognitive decline are scarce.

METHODS

This population-based cohort study included 2147 participants (age≥60) in SNAC-K who were free of dementia and regularly followed from 2001-2004 to 2013-2016. RHR was assessed with electrocardiogram. Dementia was diagnosed following the Diagnostic and Statistical Manual of Mental Disorders 4th Revision criteria. Global cognitive function was assessed using Mini-Mental State Examination (MMSE). Data were analyzed using Cox and linear mixed-effects models.

RESULTS

RHR≥80 (vs. 60-69) bpm was associated with a multi-adjusted hazard ratio of 1.55 (95% confidence interval 1.06-2.27) for dementia. The association remained significant after excluding participants with prevalent and incident CVDs. Similarly, RHR≥80 bpm was associated with a multi-adjusted β-coefficient of -0.13 (-0.21 to -0.04) for MMSE score.

DISCUSSION

Higher RHR is associated with increased risk for dementia and faster cognitive decline independent of CVDs in a general population of elderly people.

Relationship between arterial stiffness and cognitive function in outpatients with dementia and mild cognitive impairment compared with community residents without dementia

BACKGROUND

It is unclear whether the dementia patients with Alzheimer's disease (AD) and vascular dementia (VaD) and mixed dementia (MIX, including AD and VaD) would have more developed arterial stiffness as compared with local residents without dementia. The aim of this study was to assess arterial stiffness and cognitive function in different types of dementia patients [AD, VaD, MIX and mild cognitive impairment (MCI)] and community residents without dementia.

METHODS

This was a single-center, cross-sectional observational study. We studied a cohort of 600 elderly outpatients with a complaint of memory loss, who were divided into four groups (AD, VaD, MIX and MCI). In addition, they were compared with 55 age-matched local residents without dementia (Controls). We assessed arterial stiffness by brachial-ankle pulse wave velocity (baPWV) and the global cognitive function by the Mini-Mental State Examination (MMSE).

RESULTS

The baPWV was higher in AD, VaD and MIX than in MCI and in Controls (P < 0.05). The baPWV was higher in MCI than in Controls (P = 0.021), while MMSE were compatible between them (P = 0.119). The higher baPWV predicted the presence of AD, VaD, MIX and MCI with the odds ratio of 6.46, 8.74, 6.16 and 6.19, respectively. In contrast, there were no difference in baPWV among three different types of dementia (P = 0.191). The linear relationship between baPWV and MMSE was observed in the elderly with MMSE ≥ 23 (R = 0.452, P = 0.033), while it was not in dementia patients (MMSE < 23).

CONCLUSIONS

The findings suggest that MCI and dementia patients have stiffer arteries as compared with age-matched local residents, although global cognitive function may be comparable between MCI and the local residents.

Association between blood pressure control status, visit-to-visit blood pressure variability, and cognitive function in elderly Chinese: A nationwide study

Background

Cognitive function is a concern among the elderly, which is related to the quality of life, life expectancy, and economic burdens. The relationship between blood pressure (BP) control status, visit-to-visit BP variability, and cognitive function remains controversial.

Methods

We aimed to explore the association between BP control status at baseline, visit-to-visit BP variability, and cognitive function. This study included 3,511 elderlies in the China Health and Retirement Longitudinal Study, covering four waves for 7-year follow-up (baseline 2011, 2013, 2015, and 2018). BP was measured in Wave 2011, 2013, and 2015. Cognitive function was measured by Mini-Mental State Exam in Wave 2018. Participants were divided into two groups: mid-old group for reflecting midlife BP and cognition (45–59 years at baseline but aged 60 or over in Wave 2018), and old-old group for reflecting late-life BP and cognition (aged 60 or over at baseline). We use univariate analysis and general linear model to analyze.

Results

Late-life BP showed stronger associations with cognitive function than midlife BP. As to late-life BP control status, controlled hypertension group get higher cognitive score than uncontrolled hypertension group in language (adjusted β = −0.34, 95%CI −0.68 to 0.00), and untreated hypertension group in orientation (adjusted β = −0.41, 95%CI −0.72 to −0.11), language (adjusted β = −0.35, 95%CI −0.67 to −0.04), and total (adjusted β = −0.99, 95%CI −1.85 to −0.12). Regarding visit-to-visit BP variability, midlife visit-to-visit systolic blood pressure (SBP) variability was associated with language (adjusted β = −3.70, 95% CI −5.83 to −1.57), while late-life visit-to-visit SBP variability was associated with orientation (adjusted β = −2.99, 95% CI −4.84 to −1.14), recall (adjusted β = −1.69, 95% CI −2.89 to −0.48), language (adjusted β = −2.26, 95% CI −4.13 to −0.38), and total (adjusted β = −9.50, 95% CI −14.71 to −4.28); Midlife diastolic blood pressure (DBP) variability and pulse pressure (PP) variability showed a significant relationship with language (adjusted β = 3.25, 95% CI −1.31 to −5.19) and calculation (adjusted β = −0.26, 95% CI −0.47 to −0.04), respectively. No significant correlation was found between midlife BP control status, late-life visit-to-visit DBP variability, late-life visit-to-visit PP variability, and cognitive score. There was no significant correlation between BP and memory.

Conclusions

BP control status and visit-to-visit BP variability were significantly related to cognitive function among the Chinese elderly. Receiving effective late-life antihypertensive treatment and keeping SBP stable might contribute to prevent the development of cognitive impairment and dementia, especially for orientation and language function.

Decreases in Arterial Stiffness and Wave Reflection after Isometric Handgrip Training Are Associated with Improvements in Cognitive Function in Older Adults

This study aimed to investigate whether decreases in arterial stiffness and wave reflection after isometric handgrip (IHG) training improve cognitive function in older adults. Twenty-two older adults (mean age ± standard error: 75 ± 2 years) were randomly assigned to either a group that performed IHG training (IHG group, n = 11) or a sedentary control group (CON group, n = 11). The IHG exercise comprised four unilateral 2-minute isometric contractions at 30% of maximal voluntary contraction using a programmed handgrip dynamometer with 1-minute rest periods, performed 5 days per week for 8 weeks. Carotid pulse wave velocity (cPWV) and carotid augmentation index (cAIx) were measured, and the trail-making test (TMT) parts A (TMT-A) and B (TMT-B) were performed before (baseline) and after 8 weeks of training in both groups. After 8 weeks of training, cPWV, cAIx, TMT-A, and TMT-B were significantly reduced in the IHG group (p < 0.05). Significant positive correlations were found between the amount of change in cPWV and cAIx and that in TMT-A (p < 0.05 each). In addition, positive correlation trends were observed between the amount of change in cPWV and cAIx and that in TMT-B (p = 0.06, p = 0.05, respectively). The results of the present study suggest that IHG training-induced decreases in arterial stiffness and wave reflection are associated with improvements in cognitive function in older adults.

Cardiorespiratory fitness and cognition in persons at risk for Alzheimer's disease

Introduction

This study examined the relationship between cardiorespiratory fitness (CRF) and longitudinal cognitive functioning in a cohort enriched with risk factors for Alzheimer's disease (AD).

Methods

A total of 155 enrollees in the Wisconsin Registry for Alzheimer's Prevention completed repeat comprehensive neuropsychological evaluations that assessed six cognitive domains. Peak oxygen consumption (VO2peak) was the primary measure of CRF. Random effects regression was used to investigate the effect of CRF on cognitive trajectories.

Results

Higher CRF was associated with slower decline in the cognitive domains of verbal learning and memory (P < .01) and visual learning and memory (P < .042). Secondary analyses indicated that these effects were stronger among men than women, and for noncarriers of the apolipoprotein E ε4 allele.

Discussion

Higher CRF was associated with a slower rate of the decline in episodic memory that occurs as a natural consequence of aging in a cohort enriched with risk factors for AD.

Ankle-Brachial Index and Cardio-Ankle Vascular Index as Predictors of Cognitive Decline Over Time After Carotid Endarterectomy

Objective: Patients with carotid stenosis risk cognitive impairment even after carotid endarterectomy (CEA) because of the long-term presence of vascular risk factors. Early prediction of cognitive decline is useful because early appropriate training for impaired cognitive domains can improve their functions. Ankle-brachial index (ABI) and cardio-ankle vascular index (CAVI) are frequently used as general indicators of systemic atherosclerosis and are associated with cognitive function in the general population. This study aimed to evaluate the utility of those vascular biomarkers for predicting cognitive decline in patients after CEA.

Methods: Patients who had undergone both CEA at our institute and cognitive evaluations between March 2016 and January 2022 were invited to participate in this study. Associations between ABI or CAVI three years before baseline and cognitive function at baseline were assessed retrospectively in 94 patients, and associations between ABI or CAVI at baseline and three-year changes in cognitive functions were assessed prospectively in 24 patients. Cognitive functions were assessed using the Frontal Assessment Battery (FAB) and Neurobehavioral Cognitive Status Examination (Cognistat).

Results: Low ABI three years before baseline was associated with poor performances on Cognistat and FAB at baseline. ABI, as a continuous measure, three years before baseline, showed positive linear associations with total Cognistat score and subscores for naming, construction, and judgment at baseline. The Wilcoxon signed-rank test showed that the total Cognistat score, total FAB score, and subscores for attention and inhibitory control declined after three years. CAVI at baseline was negatively associated with three-year changes in total Cognistat score and subscores for naming, construction, and memory.

Conclusion: Cognitive function can decline over time in patients with carotid stenosis even after CEA. ABI and CAVI might be useful to predict cognitive function and its decline among patients who have undergone CEA.

Retinal Vascular Study Using OCTA in Subjects at High Genetic Risk of Developing Alzheimer’s Disease and Cardiovascular Risk Factors

In 103 subjects with a high genetic risk of developing Alzheimer’s disease (AD), family history (FH) of AD and ApoE ɛ4 characterization (ApoE ɛ4)) were analyzed for changes in the retinal vascular network by OCTA (optical coherence tomography angiography), and AngioTool and Erlangen-Angio-Tool (EA-Tool) as imaging analysis software. Retinal vascularization was analyzed by measuring hypercholesterolemia (HCL) and high blood pressure (HBP). Angio-Tool showed a statistically significant higher percentage of area occupied by vessels in the FH+ ApoE ɛ4- group vs. in the FH+ ApoE ɛ4+ group, and EA-Tool showed statistically significant higher vascular densities in the C3 ring in the FH+ ApoE ɛ4+ group when compared with: i)FH- ApoE ɛ4- in sectors H3, H4, H10 and H11; and ii) FH+ ApoE ɛ4- in sectors H4 and H12. In participants with HCL and HBP, statistically significant changes were found, in particular using EA-Tool, both in the macular area, mainly in the deep plexus, and in the peripapillary area. In conclusion, OCTA in subjects with genetic risk factors for the development of AD showed an apparent increase in vascular density in some sectors of the retina, which was one of the first vascular changes detectable. These changes constitute a promising biomarker for monitoring the progression of pathological neuronal degeneration.

Clinical Applications Measuring Arterial Stiffness: An Expert Consensus for the Application of Cardio-Ankle Vascular Index

BACKGROUND

The purpose of this document is to provide clinicians with guidance, using expert consensus, to help summarize evidence and offer practical recommendations.

METHODS

Expert Consensus Documents are intended to provide guidance for clinicians in areas in which there are no clinical practice guidelines, especially for new and evolving tests such as arterial stiffness measurements, until any formal guidelines are released.

RESULTS

This expert consensus document is intended as a source of information for decision-making and to guide clinician-patient discussions in various clinical scenarios.

CONCLUSIONS

The goal is to help clinicians and patients make a more informed decision together.

Arterial Stiffness and Long-Term Risk of Health Outcomes: The Framingham Heart Study

BACKGROUND

Arterial stiffness increases with age and is associated with an increased risk of adverse outcomes on short-term follow-up (typically <10 years). Data regarding associations of arterial stiffness with health outcomes on longer-term follow-up are lacking.

METHODS

We evaluated 7283 Framingham Study participants (mean age 50 years, 53% women) who underwent assessment of carotid-femoral pulse wave velocity (a marker of arterial stiffness) via applanation tonometry at one or more routine examinations. We used time-dependent Cox proportional hazards regression models to relate carotid-femoral pulse wave velocity to the incidence of health outcomes (updating carotid-femoral pulse wave velocity and all covariates at serial examinations).

RESULTS

On long-term follow-up (median 15 years; minimum-maximum, 0-20), participants developed cardiometabolic disease (hypertension [1255 events]; diabetes [381 events]), chronic kidney disease (529 events), dementia (235 events), cardiovascular disease (684 events) and its components (coronary heart disease [314 events], heart failure [191 events], transient ischemic attacks or stroke [250 events]), and death (1086 events). In multivariable-adjusted models, each SD increment in carotid-femoral pulse wave velocity was associated with increased risk of hypertension (hazard ratio [HR], 1.32 [95% CI, 1.21-1.44]), diabetes (HR, 1.32 [95% CI, 1.11-1.58]), chronic kidney disease (1.19 [95% CI, 1.05-1.34]), dementia (HR 1.27 [95% CI, 1.06-1.53]), cardiovascular disease (HR, 1.20 [95% CI, 1.06-1.36]) and its components (coronary heart disease, HR 1.37 [95% CI, 1.13-1.65]; transient ischemic attack/stroke, HR, 1.24 [95% CI, 1.00-1.53]), and death (HR, 1.29 [95% CI, 1.17-1.43]). The association with heart failure was borderline nonsignificant (HR, 1.21 [95% CI, 0.98-1.51], P=0.08).

CONCLUSIONS

Our prospective observations of a large community-based sample establish the long-term prognostic importance of arterial stiffness for multiple health outcomes.

Associations between carotid atherosclerotic plaque characteristics determined by magnetic resonance imaging and improvement of cognition in patients undergoing carotid endarterectomy

BACKGROUND

To determine the predictive value of carotid plaque characteristics for the improvement of cognition in patients with moderate-to-severe carotid stenosis after carotid endarterectomy (CEA), using vessel wall magnetic resonance imaging (MRI).

METHODS

This was a prospective cohort study. Patients with unilateral, moderate-to-severe carotid stenosis referred to the Peking University Third Hospital for CEA were prospectively recruited and underwent carotid vessel wall MRI within 1 week before CEA. We performed Montreal Cognitive Assessment (MoCA) within 1 week before and 3-4 days after CEA. The morphological and compositional characteristics of carotid plaques on MRI were evaluated. Improvement of cognition was defined as >10% increase of the total MoCA score after CEA compared with baseline. Carotid plaque characteristics were compared between patients with and without cognitive improvement.

RESULTS

In total, 105 patients (91 males; mean age, 65.5±8.4 years) were included. The volume {48.0 [interquartile range (IQR), 21.0 to 91.6] vs. 16.3 (IQR, 8.1 to 53.1) mm3; P=0.005} and cumulative slice [4.0 (IQR, 3.0 to 7.0) vs. 3.0 (IQR, 2.0 to 5.0); P=0.019] of carotid calcification, and maximum percentage of calcification area [13.1% (IQR, 6.0% to 19.8%) vs. 6.2% (IQR, 3.7% to 10.8%); P=0.004] were significantly smaller in participants with cognitive improvement compared to those without. Univariate logistic regression analysis showed that volume [odds ratio (OR) =0.994; 95% confidence interval (CI): 0.989 to 1.000; P=0.043] and cumulative slice (OR =0.823; 95% CI: 0.698 to 0.970; P=0.020) of carotid calcification, and maximum percentage of calcification area (OR =0.949; 95% CI: 0.909 to 0.991; P=0.018) were significantly correlated with cognitive improvement. After adjusting for confounding factors, these associations remained statistically or marginally significant (volume: OR =0.994; 95% CI: 0.988 to 1.000; P=0.057; maximum percentage of calcification area: OR =0.937; 95% CI: 0.890 to 0.987; P=0.014; and cumulative slice: OR =0.791; 95% CI: 0.646 to 0.967; P=0.022). No significant associations were found between other plaque characteristics and cognitive improvement (all P>0.05).

CONCLUSIONS

More than half of the participants with unilateral, moderate-to-severe carotid atherosclerotic stenosis had cognitive improvement. The size of calcification might be an effective indicator of cognitive improvement after CEA.

In Vivo Pulsatility Measurement of Cerebral Microcirculation in Rodents Using Dynamic Ultrasound Localization Microscopy

An increased pulse pressure, due to arteries stiffening with age and cardiovascular disease, may lead to downstream brain damage in microvessels and cognitive decline. Brain-wide imaging of the pulsatility propagation from main feeding arteries to capillaries in small animals could improve our understanding of the link between pulsatility and cognitive decline. However, it requires higher spatiotemporal resolution and penetration depth than currently available with existing brain imaging techniques. Herein, we show the feasibility of performing Dynamic Ultrasound Localization Microscopy (DULM), a novel imaging approach to capture hemodynamics with a subwavelength resolution. By producing cine-loops of flowing microbubbles in 2D in the whole rodent brain lasting several cardiac cycles, DULM performed pulsatility measurements in microvessels in-depth, in vivo, with and without craniotomy. Cortical veins and arteries were shown to have a significatively different pulsatility index and the method was compared against Contrast Enhanced Ultrafast Ultrasound Doppler (CEUFD) pulsatility measurements.

Carotid Artery Stiffness: Imaging Techniques and Impact on Cerebrovascular Disease

Arterial stiffness is an important measure of vascular aging and atherosclerosis. Though it is measured in many well-known epidemiologic cohort studies, arterial stiffness is often overlooked in routine clinical practice for a number of reasons including difficulties in measurement, variations in definition, and uncertainties surrounding treatment. Central arterial stiffness, a surrogate for aortic stiffness, is the most commonly measured marker of arterial stiffness. In addition to central stiffness, there are also a number of ultrasound based techniques to measure local vascular stiffness, including carotid stiffness. There is evidence that both local carotid stiffness and central arterial stiffness measures are associated with multiple cerebrovascular processes, including stroke and cognitive dysfunction. Mechanistic explanations supporting this association include increased flow load experienced by the cerebral microvasculature leading to cerebral parenchymal damage. In this article, we review definitions of carotid artery stiffness measures and pathophysiologic mechanisms underpinning its association with plaque development and downstream cerebral pathology. We will review the evidence surrounding the association of carotid stiffness measures with downstream manifestations including stroke, cerebral small vessel disease detected on brain MR such as white matter hyperintensities and covert brain infarctions, brain atrophy, and cognitive dysfunction. With consistent definitions, measurement methods, and further scientific support, carotid stiffness may have potential as an imaging-based risk factor for stroke and cognitive decline.

Pulsatile tympanic membrane displacement is associated with cognitive score in healthy subjects

To test the hypothesis that pulsing of intracranial pressure has an association with cognition, we measured cognitive score and pulsing of the tympanic membrane in 290 healthy subjects. This hypothesis was formed on the assumptions that large intracranial pressure pulses impair cognitive performance and tympanic membrane pulses reflect intracranial pressure pulses. 290 healthy subjects, aged 20-80 years, completed the Montreal Cognitive Assessment Test. Spontaneous tympanic membrane displacement during a heart cycle was measured from both ears in the sitting and supine position. We applied multiple linear regression, correcting for age, heart rate, and height, to test for an association between cognitive score and spontaneous tympanic membrane displacement. Significance was set at P < 0.0125 (Bonferroni correction.) A significant association was seen in the left supine position (p = 0.0076.) The association was not significant in the right ear supine (p = 0.28) or in either ear while sitting. Sub-domains of the cognitive assessment revealed that executive function, language and memory have been primarily responsible for this association. In conclusion, we have found that spontaneous pulses of the tympanic membrane are associated with cognitive performance and believe this reflects an association between cognitive performance and intracranial pressure pulses.

Arterial stiffness and age moderate the association between physical activity and global cognition in older adults

BACKGROUND

Evidence supports that time spent on physical activity has beneficial effects on cognition in older adults. Nevertheless, whether these beneficial effects are still present at the intersection of different levels of arterial stiffness and age is uncertain.

METHODS

One hundred and ten healthy older adults aged 60-75 years were examined for arterial stiffness [carotid-femoral pulse wave velocity (cf-PWV)], global cognition (composite score of Montreal Cognitive Assessment, and Mini-Mental State Examination), and self-reported physical activity (PACED diary). Using PROCESS macro for SPSS, we evaluated if cf-PWV (moderator 1), and age (moderator 2) moderate the relationship between physical activity (X) and global cognition (Y). The threshold for high stiffness was set at 8.5 m/s based on previous studies that reported this cut-off as more appropriate for classifying cerebrovascular risk groups.

RESULTS

Physical activity had a positive effect on cognition in young-elderly adults (<68.5 years) with a cf-PWV of at least 8.5 m/s (β = 0.48, SE = 0.193, P = 0.014, 95% CI = 0.100--0.868) and in elderly adults (≥68.5 years) with a cf-PWV of less than 8.5 m/s (β = 0.56, SE = 0.230, P = 0.017, 95% CI = 0.104-1.018). This was not the case in elderly adults with a cf-PWV of at least 8.5 m/s (β = 0.00, SE = 0.193, P = 0.998, 95% CI = -0.362 to 361), or in young-elderly adults with a cf-PWV of less than 8.5 m/s (β = 0.16, SE = 0.247, P = 0.501, 95% CI = -0.326 to 656).

CONCLUSION

The interaction between arterial stiffness and age moderated the effect of physical activity on global cognition. Time spent on physical activity alone might not be sufficient to achieve cognitive benefit over a specific threshold of arterial stiffness and age.

Relationship Between Arterial Stiffness Index, Pulse Pressure, and Magnetic Resonance Imaging Markers of White Matter Integrity: A UK Biobank Study

Background

Alzheimer's disease and dementia in general constitute one of the major public health problems of the 21st century. Research in arterial stiffness and pulse pressure (PP) play an important role in the quest to reduce the risk of developing dementia through controlling modifiable risk factors.

Objective

The aim of the study is to investigate the association between peripheral PP, arterial stiffness index (ASI) and brain integrity, and to discover if ASI is a better predictor of white matter integrity than peripheral PP.

Materials and Methods

17,984 participants 63.09 ± 7.31 from the UK Biobank were used for this study. ASI was estimated using infrared light (photoplethysmography) and peripheral PP was calculated by subtracting the diastolic from the systolic brachial blood pressure value. Measure of fractional anisotropy (FA) was obtained from diffusion imaging to estimate white matter microstructural integrity. White matter hyperintensities were segmented from the combined T1 and T2-weighted FLAIR images as a measure of irreversible white matter damage.

Results

An important finding is that peripheral PP better predicts white matter integrity when compared to ASI. This finding is consistent until 75 years old. Interestingly, no significant relationship is found between either peripheral PP or ASI and white matter integrity after 75 years old.

Conclusion

These results suggest that ASI from plethysmography should not be used to estimate cerebrovascular integrity in older adults and further question the relationship between arterial stiffness, blood pressure, and white matter damage after the age of 75 years old.

Burden and correlates of cognitive impairment among hypertensive patients in Tanzania: a cross-sectional study

BACKGROUND

The evolution of cognitive impairment of vascular origin is increasingly becoming a prominent health threat particularly in this era where hypertension is the leading contributor of global disease burden and overall health loss. Hypertension is associated with the alteration of the cerebral microcirculation coupled by unfavorable vascular remodeling with consequential slowing of mental processing speed, reduced abstract reasoning, loss of linguistic abilities, and attention and memory deficits. Owing to the rapidly rising burden of hypertension in Tanzania, we sought to assess the prevalence and correlates of cognitive impairment among hypertensive patients attending a tertiary cardiovascular hospital in Tanzania.

METHODOLOGY

A hospital-based cross-sectional study was conducted at Jakaya Kikwete Cardiac Institute, a tertiary care public teaching hospital in Dar es Salaam, Tanzania between March 2020 and February 2021. A consecutive sampling method was utilized to recruit consented hypertensive outpatients during their scheduled clinic visit. General Practitioner Assessment of Cognition (GPCOG) Score was utilized in the assessment of cognitive functions. All statistical analyses utilized STATA v11.0 software. Pearson Chi square and Student's T-test were used to compare categorical and continuous variables respectively. Logistic regression analyses were used to assess for factors associated with cognitive impairment. Odd ratios with 95% confidence intervals and p-values are reported. All tests were 2-sided and p < 0.05 was used to denote a statistical significance.

RESULTS

A total of 1201 hypertensive patients were enrolled in this study. The mean age was 58.1 years and females constituted nearly two-thirds of the study population. About three quarters had excess body weight, 16.6% had diabetes, 7.7% had history of stroke, 5.7% had heart failure, 16.7% had renal dysfunction, 53.7% had anemia, 27.7% had hypertriglyceridemia, 38.5% had elevated LDL, and 2.4% were HIV-infected. Nearly two-thirds of participants had uncontrolled blood pressure and 8.7% had orthostatic hypotension. Overall, 524 (43.6%) of participants had cognitive impairment. During bivariate analysis in a logistic regression model of 16 characteristics, 14 parameters showed association with cognitive functions. However, after controlling for confounders, multivariate analysis revealed ≤primary education (OR 3.5, 95%CI 2.4-5.2, p < 0.001), unemployed state (OR 1.7, 95%CI 1.2-2.6, p < 0.01), rural habitation (OR 1.8, 95%CI 1.1-2.9, p = 0.01) and renal dysfunction (OR 1.7, 95%CI 1.0-2.7, p = 0.04) to have independent association with cognitive impairment.

CONCLUSION

This present study underscore that cognitive decline is considerably prevalent among individuals with systemic hypertension. In view of this, it is pivotal to incorporate cognitive assessment in routine evaluation of hypertensive patients.

The Influence of Sedentary Behavior on the Relationship Between Cognitive Function and Vascular Function in Older Adults with and without Chronic Kidney Disease

Cognitive impairment and vascular dysfunction are common in older adults with and without chronic kidney disease (CKD). Older adults with and without CKD are also sedentary - a behavior associated with cognitive and vascular function. The objective of this study was to explore whether sedentary behavior influenced the relationship between cognitive and vascular function in older adults with preclinical cognitive impairment with and without CKD. In our study, 48 older adults underwent assessment of cognition, vascular compliance, and sedentary behavior, and relationships were explored with regression moderation analysis. Sedentary time and breaks did not moderate the relationship between vascular and cognitive function. Although significant moderation was not found, cognition, vascular function, and sedentary behavior are important to assess when evaluating older adults with and without CKD.

Carotid Compliance and Parahippocampal and Hippocampal Volume over a 20-Year Period

INTRODUCTION

We evaluated the association between carotid compliance, a measure of arterial stiffness, to parahippocampal volume (PHV) and hippocampal volume (HV) over 20 years later in the Atherosclerosis Risk in the Community study.

METHODS

We included participants with common carotid compliance measurements at visit 1 (1987-1989) and volumetric brain MRI at visit 5 (2011-2013). The primary outcomes are pooled bilateral PHV and HV. We performed linear regression models adjusting for age, sex, vascular risk factors, and total brain volume.

RESULTS

Of the 614 participants, higher compliance was correlated with higher PHV (R = 0.218[0.144-0.291], p < 0.001) and HV (R = 0.181 [0.105-0.255, p < 0.001]). The association was linear and significant after adjusting for confounders. At follow-up MRI, 30 patients with dementia had lower PHV and HV than patients without dementia (p < 0.001 and p < 0.001, respectively).

CONCLUSION

Carotid compliance is associated with higher PHV and HV when measured 20 years later, further supporting the link between arterial stiffness and cognitive decline.

Higher habitual dietary flavonoid intake associates with lower central blood pressure and arterial stiffness in healthy older adults

Flavonoids have shown anti-hypertensive and anti-atherosclerotic properties: the impact of habitual flavonoid intake on vascular function, central haemodynamics and arterial stiffness may be important. We investigated the relationship between habitual flavonoid consumption and measures of central blood pressure and arterial stiffness. We performed cross-sectional analysis of 381 non-smoking healthy older adults (mean age 66·0 (sd 4·1) years; BMI, 26·4 (sd 4·41) kg/m2; 41 % male) recruited as part of the Australian Research Council Longevity Intervention study. Flavonoid intake (i.e. flavonols, flavones, flavanones, anthocyanins, isoflavones, flavan-3-ol monomers, proanthocyanidins, theaflavins/thearubigins and total consumption) was estimated from FFQ using the US Department of Agriculture food composition databases. Measures of central haemodynamics and arterial stiffness included systolic blood pressure (cSBP), diastolic blood pressure (cDBP), mean arterial pressure (cMAP) and augmentation index (cAIx). After adjusting for demographic and lifestyle confounders, each sd/d higher intake of anthocyanins ((sd 44·3) mg/d) was associated with significantly lower cDBP (-1·56 mmHg, 95 % CI -2·65, -0·48) and cMAP (-1·62 mmHg, 95 % CI -2·82, -0·41). Similarly, each sd/d higher intake of flavanones ((sd 19·5) mg/d) was associated with ~1 % lower cAIx (-0·93 %, 95 % CI -1·77, -0·09). These associations remained significant after additional adjustment for (1) a dietary quality score and (2) other major nutrients that may affect blood pressure or arterial stiffness (i.e. Na, K, Ca, Mg, n-3, total protein and fibre). This study suggests a possible benefit of dietary anthocyanin and flavanone intake on central haemodynamics and arterial stiffness; these findings require corroboration in further research.

Association of Aortic Stiffness and Cognitive Decline: A Systematic Review and Meta-Analysis

Background: Increased aortic stiffness has been found to be associated with cognitive function decline, but the evidence is still under debate. It is of great significance to elucidate the evidence in this debate to help make primary prevention decisions to slow cognitive decline in our routine clinical practice.

Methods: Electronic databases of PubMed, EMBASE, and Cochrane Library were systematically searched to identify peer-reviewed articles published in English from January 1, 1986, to March 16, 2020, that reported the association between aortic stiffness and cognitive function. Studies that reported the association between aortic pulse wave velocity (PWV) and cognitive function, cognitive impairment, and dementia were included in the analysis.

Results: Thirty-nine studies were included in the qualitative analysis, and 29 studies were included in the quantitative analysis. The aortic PWV was inversely associated with memory and processing speed in the cross-sectional analysis. In the longitudinal analysis, the high category of aortic PWV was 44% increased risk of cognitive impairment (OR 1.44; 95% CI 1.24–1.85) compared with low PWV, and the risk of cognitive impairment increased 3.9% (OR 1.039; 95% CI 1.005–1.073) per 1 m/s increase in aortic PWV. Besides, meta-regression analysis showed that age significantly increased the association between high aortic PWV and cognitive impairment risk.

Conclusion: Aortic stiffness measured by aortic PWV was inversely associated with memory and processing speed and could be an independent predictor for cognitive impairment, especially for older individuals.

Longer Duration of Hypertension and MRI Microvascular Brain Alterations Are Associated with Lower Hippocampal Volumes in Older Individuals with Hypertension

BACKGROUND

Hippocampal atrophy is associated with cognitive decline. Determining the clinical features associated with hippocampal volume (HV)/atrophy may help in tailoring preventive strategies.

OBJECTIVE

This study was aimed to investigate the association between HV (at visit 2) and vascular status (both at visit 1 and visit 2) in a cohort of individuals aged 60+ with hypertension and without overt cognitive impairment at visit 1 (visit 1 and visit 2 were separated by approximately 8 years).

METHODS

Hippocampal volume was estimated in brain MRIs as HV both clinically with the Scheltens' Medial Temporal Atrophy score, and automatically with the Free Surfer Software application. A detailed medical history, somatometric measurements, cognitive tests, leukoaraiosis severity (Fazekas score), vascular parameters including pulse wave velocity, central blood pressure, and carotid artery plaques, as well as several biochemical parameters were also measured.

RESULTS

113 hypertensive patients, 47% male, aged 75.1±5.6 years, participated in both visit 1 and visit 2 of the ADELAHYDE study. Age (β= -0.30) and hypertension duration (β= -0.20) at visit 1 were independently associated with smaller HV at visit 2 (p < 0.05 for all). In addition to these variables, low body mass index (β= 0.18), high MRI Fazekas score (β= -0.20), and low Gröber-Buschke total recall (β= 0.27) were associated with smaller HV at visit 2 (p < 0.05 for all).

CONCLUSION

In a cohort of older individuals without cognitive impairment at baseline, we described several factors associated with lower HV, of which hypertension duration can potentially be modified.

Effects of coffee consumption on arterial stiffness and endothelial function: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Endothelial function (EF) and arterial stiffness (AS) are predictors of cardiovascular disease. As previous research concerning the effect of coffee intake on EF and AS was controversial, we conducted a systematic review and meta-analysis to synthesize research.

METHODS

We performed a systematic search in PubMed, Scopus and Web of Science to find clinical trials investigating the effect of coffee intake on EF or AS up to March 2020.Random-effects models were used to estimate the pooled weighted mean difference (WMD) between intervention and control groups for randomized controlled trials (RCTs). Between study heterogeneity was estimated using Cochran's Q and the I ²-inconsistency index. Internal validity of included randomized trials was determined with the Cochrane Collaboration's tool for assessing the risk of bias.

RESULTS

Twenty-three articles were included for qualitative and 11 articles for quantitative synthesis. Meta-analysis of 14 RCTs (nine articles) indicated a positive short-term (postprandial) effect of coffee intake on flow-mediated dilation (FMD) as a measure of EF (WMD: 1.93%[95% CI: 1.10-2.75]; I ²= 97.9%). Meta-analysis of three long-term RCTs(two articles) found no such effect on FMD (WMD: -0.08% [-3.82 to 3.66]; I ²= 61.4%).Most short-term information was from studies at low or unclear risk of bias, while the proportion of long-term information from studies at high risk of bias was considerable.

CONCLUSION

The results from this meta-analysis suggest a beneficial short-term effect of coffee intake on EF as measured by FMD. However, there might be unfavorable effects on AS. Our findings must be interpreted cautiously as the number of studies were low and included studies had a considerable risk of bias.

The Potential Mediation of the Effects of Physical Activity on Cognitive Function by the Gut Microbiome

The population of older adults is growing dramatically worldwide. As older adults are at greater risk of developing disorders associated with cognitive dysfunction (i.e., dementia), healthcare costs are expected to double by 2040. Evidence suggests dementia may be slowed or prevented by lifestyle interventions, including physical activity (PA). PA is associated with improved cognitive function and may reduce risk for dementia by mitigating known risk factors (i.e., cardiovascular diseases) and/or by enhancing neurochemical processes. An emerging area of research suggests the gut microbiome may have similar neuroprotective effects. Altering the gut microbiome has been found to target physiological processes associated with dementia risk, and it influences gut-brain-microbiome axis signaling, impacting cognitive functioning. The gut microbiome can be altered by several means (i.e., disease, diet, prebiotics, probiotics), including PA. As PA and the gut microbiome independently influence cognitive function and PA changes the composition of the gut microbiome, cognitive improvement due to PA may be partially mediated by the gut microbiome. The present article provides an overview of the literature regarding the complex associations among PA, cognitive function, and the gut microbiome, as well as their underlying biological mechanisms. A comprehensive, theoretical model integrating evidence for the potential mediation is proposed.

Arterial Stiffness Due to Carotid Calcification Disrupts Cerebral Blood Flow Regulation and Leads to Cognitive Deficits

Background

Arterial stiffness is associated with cognitive decline and dementia; however, the precise mechanisms by which it affects the brain remain unclear.

Methods and Results

Using a mouse model based on carotid calcification this study characterized mechanisms that could contribute to brain degeneration due to arterial stiffness. At 2 weeks postcalcification, carotid stiffness attenuated resting cerebral blood flow in several brain regions including the perirhinal/entorhinal cortex, hippocampus, and thalamus, determined by autoradiography (P<0.05). Carotid calcification impaired cerebral autoregulation and diminished cerebral blood flow responses to neuronal activity and to acetylcholine, examined by laser Doppler flowmetry (P<0.05, P<0.01). Carotid stiffness significantly affected spatial memory at 3 weeks (P<0.05), but not at 2 weeks, suggesting that cerebrovascular impairments precede cognitive dysfunction. In line with the endothelial deficits, carotid stiffness led to increased blood‐brain barrier permeability in the hippocampus (P<0.01). This region also exhibited reductions in vessel number containing collagen IV (P<0.01), as did the somatosensory cortex (P<0.05). No evidence of cerebral microhemorrhages was present. Carotid stiffness did not affect the production of mouse amyloid‐β (Aβ) or tau phosphorylation, although it led to a modest increase in the Aβ40/Aβ42 ratio in frontal cortex (P<0.01).

Conclusions

These findings suggest that carotid stiffness alters brain microcirculation and increases blood‐brain barrier permeability associated with cognitive impairments. Therefore, arterial stiffness should be considered a relevant target to protect the brain and prevent cognitive dysfunctions.

Role of Changes in State of Bound Water and Tissue Stiffness in Development of Age-Related Diseases

An essential effect of environmental stiffness on biological processes in cells at present is generally accepted. An increase in arterial stiffness with advanced age has been reported in many publications. The aim of the present review is to summarize current information about possible chemical reactions and physical processes that lead to tissue stiffening and result in age-related diseases in order to find methods that can prevent or retard time-dependent tissue stiffening. The analysis of published data shows that bound water acts as a plasticizer of biological tissues, a decrease in bound water content results in an increase in biological tissue stiffness, and increased tissue stiffness leads to NF-kB activation and triggered actin polymerization-NF-kB activation is associated with age-related diseases. It can be suggested that changes in bound water content through changing tissue stiffness can affect cellular processes and the development of pathologies related to aging. Both age-related diseases and COVID-19 may be associated with tight-junction disruption and increased tissue stiffness and permeability.

Relationship between motoric cognitive risk syndrome, cardiovascular risk factors and diseases, and incident cognitive impairment: Results from the "NuAge" study

BACKGROUND

Motoric Cognitive Risk syndrome (MCR), which combines Subjective Cognitive Complaint (SCC) and slow gait speed in individuals free of dementia and gait disability, is associated with cardiovascular risk factors and diseases as well as incident cognitive impairment. Little information on MCR exists in the Canadian population. This study aims to examine these associations in community-dwelling elderly people living in Quebec, which is a Canadian province.

METHODS

Data was collected from the"Nutrition as a determinant of successful aging: The Quebec longitudinal study" (NuAge), which is a Quebec population-based observational cohort study with 3 years of follow-up. A subset of 1113 participants (age 73.8 ± 4.1 and 51.9% female; 63.5% of the initial NuAge sample) was selected. MCR, cardiovascular risk factors and disease were recorded at baseline. Incident cognitive impairment was considered if the Modified Mini-Mental State Examination (3MS) score was ≤79/100 at subsequent annual visits.

RESULTS

The prevalence of MCR was 4.2% at baseline and was significantly associated with diabetes (P < 0.032), cerebrovascular disease (P < 0.043) and incident cognitive impairment (P ≤ 0.001). The overall incidence of cognitive impairment during the 3-year follow-up period was 4.6%. A greater decrease of the 3MS score was observed in participants with MCR compared to those without MCR, at each annual assessment (P ≤ 0.001).

CONCLUSION

MCR was associated with diabetes and cerebrovascular diseases at baseline, and incident cognitive impairment in NuAge study participants.

Carotid Artery Stiffness is Associated With Cognitive Performance in Former Smokers With and Without Chronic Obstructive Pulmonary Disease

Background

Heavy smokers perform worse on neuropsychological assessment than age‐matched peers. However, traditional pulmonary measures of airflow limitation and hypoxemia explain only a modest amount of variance in cognition. The current objective was to determine whether carotid artery stiffness is associated with cognition in former smokers beyond the effects of amount of smoking and pulmonary function.

Methods and Results

Eighty‐four former smokers including individuals across a spectrum of airflow limitation severity were included: 30 without chronic obstructive pulmonary disease (Global Initiative for Chronic Obstructive Lung Disease [GOLD] 0 with normal spirometry and lung computed tomography), 31 with mild‐moderate chronic obstructive pulmonary disease (GOLD 1–2), and 23 with severe‐very severe chronic obstructive pulmonary disease (GOLD 3–4). Participants completed questionnaires, spirometry, carotid ultrasonography, and neuropsychological testing. Multiple linear regression was used to determine whether carotid artery stiffness is associated with neuropsychological performance in 4 cognitive domains after adjusting for age, sex, pack‐years of smoking, estimated premorbid intellectual functioning, and airflow limitation. Higher carotid artery β‐stiffness index was associated with reduced executive functioning‐processing speed in the fully adjusted model (β=−0.49, SE=0.14; P=0.001). Lower premorbid intellectual function, male sex, and presence of airflow limitation (GOLD 1 or 2 and GOLD 3 or 4) were also associated with worse executive functioning‐processing speed. β‐Stiffness index was not significantly associated with performance in other cognitive domains.

Conclusions

Carotid artery stiffness is associated with worse performance on executive functioning‐processing speed in former smokers beyond the effects of aging, amount of past smoking, severity of airflow limitation, and hypoxemia. Future research should examine whether carotid stiffness can be used to identify former smokers at risk for subsequent cognitive impairment.

Effects of Whey Protein Supplementation on Aortic Stiffness, Cerebral Blood Flow, and Cognitive Function in Community-Dwelling Older Adults: Findings from the ANCHORS A-WHEY Clinical Trial

ANCHORS A-WHEY was a 12-week randomized controlled trial (RCT) designed to examine the effect of whey protein on large artery stiffness, cerebrovascular responses to cognitive activity and cognitive function in older adults. Methods: 99 older adults (mean ± SD; age 67 ± 6 years, BMI 27.2 ± 4.7kg/m², 45% female) were randomly assigned to 50g/daily of whey protein isolate (WPI) or an iso-caloric carbohydrate (CHO) control for 12 weeks (NCT01956994). Aortic stiffness was determined as carotid-femoral pulse wave velocity (cfPWV). Aortic hemodynamic load was assessed as the product of aortic systolic blood pressure and heart rate (Ao SBP × HR). Cerebrovascular response to cognitive activity was assessed as change in middle-cerebral artery (MCA) blood velocity pulsatility index (PI) during a cognitive perturbation (Stroop task). Cognitive function was assessed using a computerized neurocognitive battery. Results: cfPWV increased slightly in CHO and significantly decreased in WPI (p < 0.05). Ao SBP × HR was unaltered in CHO but decreased significantly in WPI (p < 0.05). Although emotion recognition selectively improved with WPI (p < 0.05), WPI had no effect on other domains of cognitive function or MCA PI response to cognitive activity (p > 0.05 for all). Conclusions: Compared to CHO, WPI supplementation results in favorable reductions in aortic stiffness and aortic hemodynamic load with limited effects on cognitive function and cerebrovascular function in community-dwelling older adults.

Screening for cognitive impairment among the elderly attending the noncommunicable diseases clinics in a rural area of Punjab, North India

BACKGROUND

Amongst all the ailments among the elderly persons, cognitive impairment has significant impact on the quality of life. Non-communicable diseases (NCDs) like diabetes and hypertension increase the risk of cognitive impairment and dementia. Little is known about the prevalence and correlates of cognitive impairment in elderly with NCDs.

AIM

The present study aimed to evaluate the prevalence and correlates of cognitive impairment among elderly patients living with NCDs.

METHODOLOGY

297 patients attending the chronic disease clinic of two Community Health Centres were evaluated using Hindi mini-mental scale (HMSE), University of California Los Angeles Loneliness Scale (UCLA LS), Geriatric Depression Scale, Generalized Anxiety Disorder (GAD-7 scale) and Vulnerability to Abuse Screening Scale.

RESULTS

More than one-fourth (27.3 %) of participants had cognitive impairment as per the HMSE scores. The mean HMSE score was lowest (23.90+6.61) among patients with hypertension followed by patients with diabetes alone (26.90+4.46). People with hypertension had lower mean scores on all the domains of HMSE. Multivariable binary logistic regression depicted younger age, high education status, per capita income, long duration of diseases, loneliness, and hypertension emerged as the significant risk factors associated with cognitive impairment.

CONCLUSION

Older adults with non-communicable diseases have high prevalence of cognitive impairment. Physicians should make the patients and their family members aware about the association of non-communicable diseases with cognitive impairments and should encourage these persons to use remedial measures to reduce the risk of future development of dementia.

Chronic and acute effects of cocoa products intake on arterial stiffness and platelet count and function: A systematic review and dose-response Meta-analysis of randomized clinical trials

The findings of trials investigating the effect of cocoa products consumption on vascular stiffness and platelet are controversial. The aim of this study is to summarize the findings on the acute and chronic effects of different forms of cocoa on the risk factors of cardiovascular disease. We searched SCOPUS, Pub Med and Web of Science from inception to Jan 2020. Finally, the random-effect model was used to report the pooled effect sizes. Results are expressed as weighted mean difference (WMD) with 95% confidence intervals (CI).Overall, 41 trials were included, of which only 14 studies met the eligibility criteria for analysis, including 11 long-term RCTs (more than a week was considered as a chronic phase) and 7 short-term RCTs (less than a week was considered as an acute phase). According to the result of 11 long-term RCTs, cocoa products had a negative significant effect on pulse wave velocity; PWV (WMD: -0.33 m/s, P < 0.0001), Augmentation index; AIx (WMD: -4.50%, P = 0.001) but had no significant effect on platelet count (WMD: -10.41 10⁹/L, P = 0.053). Also, according to the results of 7 short-term RCTs, cocoa products had a negative significant effect on PWV (WMD: -0.27 m/s, P = 0.019), AIx (WMD: -4.47%, P = 0.003).Current study indicated the beneficial effect of acute and chronic consumption of cocoa-based products ingestion on platelet function and arterial stiffness in healthy adult regardless of age especially in male and for consumption (≤4 weeks) in the chronic intake and (≤120 minutes) in acute intake, but did not affect on platelet count. However, further studies are required to shed light on this issue.

Arterial Stiffness and Cognition Among Adults: A Systematic Review and Meta-Analysis of Observational and Longitudinal Studies

Background

To estimate the strength of the cross‐sectional and longitudinal association between arterial stiffness, measured by pulse‐wave velocity, and cognitive function, distinguishing between global cognition, executive functions, and memory and to examine the influence of demographic, clinical, and assessment characteristics on this relationship.

Methods and Results

Systematic review of MEDLINE (via PubMed), Scopus, and WOS databases from their inception to March 2019, to identify cross‐sectional and longitudinal studies on the association between pulse‐wave velocity and cognitive domains (ie, global cognition, executive functions, and memory) among adult population. A total of 29 cross‐sectional and 9 longitudinal studies support the negative relationship between arterial stiffness and cognitive function, including global cognition, executive function, and memory. Demographic, clinical, and assessment characteristics did not substantially modify the strength of this association.

Conclusions

Evidence reveals a negative association between arterial stiffness, measured using pulse‐wave velocity, and cognition, specifically executive function, memory, and global cognition. This association seems to be independent of demographic, clinical, and assessment characteristics. These results accumulate evidence supporting that pulse‐wave velocity assessment could be a useful tool to identify individuals at high risk of cognitive decline or early stages of cognitive decline, to implement interventions aimed at slowing the progression to dementia.

Aortic Stiffness and Age With Cognitive Performance Decline in the ELSA-Brasil Cohort

Background Increased aortic stiffness has been associated with cognitive decline and dementia, but the results are inconsistent. This study investigated the longitudinal association of aortic stiffness and age with decreased cognitive performance in 3 cognitive tests. Methods and Results This study included 6927 participants, with a mean age of 58.8 years at baseline (2008-2010), who participated in the second wave (2012-2014) of the ELSA-Brasil (Brazilian Longitudinal Study of Adult Health) (interval between visits ranging from 2-6 years). Cognitive performance was evaluated by Memory, Phonemic, and Semantic Verbal Fluency and Trail B Tests, applied at both cohort visits. Associations with the carotid-femoral pulse wave velocity and age at baseline were investigated using linear models with mixed effects after adjusting for confounders. After all the adjustments, including for systolic blood pressure, the interaction term carotid-femoral pulse wave velocity×time proved to be statistically significant for Memory and Verbal Fluency Tests, indicating that the higher carotid-femoral pulse wave velocity at baseline was associated with a faster decline in cognitive performance in these tests between waves. The interaction term age×time was statistically significant for all cognitive tests, suggesting that increasing age at baseline was also associated with a faster decline in cognitive performance between waves. Conclusions In this relatively young cohort, and after a relatively short interval, an increased aortic stiffness at baseline was associated with a sharper decline in cognitive performances in memory and verbal fluency, regardless of systolic blood pressure levels. This study also showed that the decline in cognitive performance was faster among older individuals than among younger ones at baseline.

Association of Blood Pressure and Arterial Stiffness With Cognition in 2 Population-Based Child and Adult Cohorts

Background

High blood pressure levels and higher arterial stiffness have been shown to be associated with lower cognition during adulthood, possibly by accumulative changes over time. However, vascular factors may already affect the brain during early life.

Methods and Results

We examined the relation between cognition and vascular factors within 5853 children from the Generation R Study (mean age 6.2 years) and 5187 adults from the Rotterdam Study (mean age 61.8 years). Diastolic and systolic blood pressure and arterial stiffness were assessed, the latter by measuring pulse‐wave velocity and pulse pressure. For cognition, the Generation R Study relied on nonverbal intelligence, whereas the Rotterdam Study relied on a cognitive test battery to calculate the g‐factor, a measure of global cognition. In the Generation R Study, standardized diastolic blood pressure showed a significant association with standardized nonverbal intelligence (β=−0.030, 95% confidence interval=[−0.054; −0.005]) after full adjustment. This association held up after excluding the top diastolic blood pressure decile (β=−0.042 [−0.075; −0.009]), suggesting that the relation holds in normotensives. Within the Rotterdam Study, standardized cognition associated linearly with standardized systolic blood pressure (β=−0.036 [−0.060; −0.012]), standardized pulse‐wave velocity (β=−0.064 [−0.095; −0.033]), and standardized pulse pressure (β=−0.044 [−0.069; −0.020], and nonlinearly with standardized diastolic blood pressure (quadratic term β=−0.032 [−0.049; −0.015]) after full adjustment.

Conclusions

Blood pressure and cognition may already be related in the general population during early childhood, albeit differently than during adulthood.

See Editorial by Ferreira

Aortic Stiffness is Associated with Increased Risk of Incident Dementia in Older Adults

Cardiovascular disease risk factors, including age, hypertension, and diabetes, contribute to aortic stiffness and subclinical cardiovascular and brain disease, increasing dementia risk. Aortic stiffness, measured by carotid-femoral pulse wave velocity (cfPWV), reduces the buffering of pulsatile blood flow, exposing cerebral small arteries to microvascular damage. High cfPWV is related to white matter hyperintensities and brain amyloid deposition, and to cognitive decline, but it is unclear whether cfPWV independently predicts incident dementia. Therefore, we tested the hypothesis that cfPWV predicts incident dementia in older adults, independent of potential confounders. The Cardiovascular Health Study Cognition Study followed 532 non-demented older adults with annual cognitive exams from 1998-99 through 2013. CfPWV was measured on 356 (mean age = 78, 59% women) between 1996-2000. Over 15 years, 212 (59.6%) developed dementia (median time from cfPWV measurement = 4 years). In age and sex-adjusted Cox models, cfPWV was significantly associated with increased risk of dementia, but systolic blood pressure, mean arterial pressure and pulse pressure were not. CfPWV (transformed as - 1/cfPWV) remained significantly associated with dementia risk when further adjusted for education, race, APOEɛ4, diabetes, body mass index, mean arterial pressure, and anti-hypertensive medication (hazard ratio = 1.60, 95% CI = 1.02, 2.51). Results were similar when further adjusted for baseline global cognition, subclinical brain measures, and coronary artery calcification. Finally, higher cfPWV was related to lower physical activity intensity and higher systolic blood pressure, heart rate, and waist circumference measured 5 years prior. An important unanswered question is whether interventions to slow arterial stiffening can reduce the risk of dementia.

Associations Between Blood Pressure and Arterial Stiffness With Cognition: Neuroaggression or Neuroselection?

See Article by Lamballais et al.

Cerebral Vascular Reactivity in Frail Older Adults with Vascular Cognitive Impairment

Background: Frailty, a state of increased vulnerability, could play a role in the progression of vascular dementia. We aim to describe the changes in cerebrovascular reactivity of older adults with frailty and vascular-type mild cognitive impairment (MCIv). Methods: This was a cross-sectional study. A comprehensive geriatric assessment, neuropsychological evaluation, and transcranial Doppler ultrasound (TCD) was performed on 180 participants who were allocated into four groups: healthy (n = 74), frail (n = 40), MCIv (n = 35), and mixed (frail + MCIv) (n = 31). ANOVA and Kruskal–Wallis tests were used for the analysis of continuous variables with and without normal distribution. Multinomial logistic regression was constructed to identify associated covariates. Results: Subjects in the mixed group, compared to healthy group, were older (75.0 ± 5.9 vs 70.3 ± 5.9 years; p < 0.001), showed lower education (9.3 ± 6.4 vs 12.2 ± 4.0 years; p = 0.054), greater frequency of diabetes (42% vs 12%; p = 0.005), worse cognitive performance (z = −0.81 ± 0.94), and reduced left medial-cerebral artery cerebrovascular reactivity (0.43 ± 0.42 cm/s). The mixed group was associated with age (odds ratio (OR) 1.16, 95% Confidence Interval (CI) = 1.06–1.27; p < 0.001), diabetes (OR 6.28, 1.81–21.84; p = 0.004), and Geriatric Depression Scale (GDS) score (OR 1.34, 95% CI = 1.09–1.67; p = 0.007). Conclusions: Frailty among older adults was associated with worse cognitive performance, diabetes, and decreased cerebral blood flow.

Arterial stiffness and brain integrity: A review of MRI findings

BACKGROUND

Given the increasing incidence of vascular diseases and dementia, a better understanding of the cerebrovascular changes induced by arterial stiffness is important for early identification of white and gray matter abnormalities that might antedate the appearance of clinical cognitive symptoms. Here, we review the evidence from neuroimaging demonstrating the impact of arterial stiffness on the aging brain.

METHOD

This review presents findings from recent studies examining the association between arterial stiffness, cognitive function, cerebral hypoperfusion, and markers of neuronal fiber integrity using a variety of MRI techniques.

RESULTS

Overall, changes associated with arterial stiffness indicates that the corpus callosum, the internal capsule and the corona radiata may be the most vulnerable regions to microvascular damage. In addition, the microstructural integrity of these regions appears to be associated with cognitive performance. Changes in gray matter structure have also been found to be associated with arterial stiffness and are present as early as the 5th decade. Moreover, low cerebral perfusion has been associated with arterial stiffness as well as lower cognitive performance in age-sensitive tasks such as executive function.

CONCLUSION

Considering the established relationship between arterial stiffness, brain and cognition, this review highlights the need for future studies of brain structure and function in aging to implement measurements of arterial stiffness in parallel with quantitative imaging.

Pulse Wave Velocities Derived From Cuff Ambulatory Pulse Wave Analysis

Pulse wave velocity (PWV), a measure of arterial stiffness, is an independent risk factor for cardiovascular morbidity and mortality. We investigated the relationship of ambulatory brachial cuff-based oscillometric PWV (oPWV) to 2 known correlates: age and brachial systolic blood pressure (SBP). In 234 participants in the Masked Hypertension Study, we analyzed 7284 validated hourly ambulatory SBP and oPWV readings using the Mobil-O-Graph monitor, which uses a proprietary pulse wave analysis algorithm to determine oPWV. Carotid-femoral PWV (cfPWV) was also measured. Mixed linear models were developed to estimate oPWV from age and ambulatory SBP. Participants were 34% male, with mean (SD) age 52.8 (9.9) years, SBP 123.8 (18.4) mm Hg, and oPWV 7.6 (1.3) m/s and cfPWV of 7.7 (1.7) m/s. The relationship of oPWV to age and SBP is given below: [Formula: see text] Age uniquely accounted for an estimated 75% of the total variation of oPWV, whereas SBP uniquely accounted for 20%; these findings were confirmed in an external validation dataset. Together, age and SBP accounted for 99.1% of the total variance of oPWV but (only) 40.2% of the variance of cfPWV. The correlation between oPWV and cfPWV was 0.58 but was only 0.11 after controlling for age and SBP. We conclude that the Mobil-O-Graph's oPWV is nearly completely explained by age and SBP and its relationship to cfPWV is because of their shared associations with age and SBP. Other hemodynamic variables derived from oscillometric pulse wave analysis may be useful and deserve additional scrutiny.

Arterial stiffness induced by carotid calcification leads to cerebral gliosis mediated by oxidative stress

BACKGROUND

Arterial stiffness is a risk factor for cognitive decline and dementia. However, its precise effects on the brain remain unexplored. Using a mouse model of carotid stiffness, we investigated its effect on glial activation and oxidative stress.

METHODS

Arterial stiffness was induced by the application of calcium chloride to the adventitial region of the right carotid. Superoxide anion production, NADPH activity and levels, as well as glial activation were examined with immunohistochemical and biochemical approaches, 2-week postcalcification. Antioxidant treatment was done with Tempol (1 mmol/l) administered in the drinking water during 2 weeks.

RESULTS

The current study revealed that arterial stiffness increases the levels of the microglial markers ionized calcium-binding adapter molecule 1 and cluster of differentiation 68 in hippocampus, and of the astrocyte marker, s100 calcium binding protein β in hippocampus and frontal cortex. The cerebral inflammatory effects of arterial stiffness were specific to the brain and not due to systemic inflammation. Treatment with Tempol prevented the increase in superoxide anion in mice with carotid stiffness and attenuated the activation of microglia and astrocytes in the hippocampus. To determine whether the increased oxidative stress derives from NADPH oxidase, superoxide anion production was assessed by incubating brain tissue in the presence of gp91ds-tat, a selective NADPH oxidase 2 inhibitor. This peptide inhibited superoxide anion production to a greater extent in the brains of mice with carotid calcification compared with controls.

CONCLUSION

Carotid calcification leads to cerebral gliosis mediated by oxidative stress. Correcting arterial stiffness could offer a novel paradigm to protect the brain in populations where stiffness is prominent.

A Review and Hypothesized Model of the Mechanisms That Underpin the Relationship Between Inflammation and Cognition in the Elderly

Age is associated with increased risk for several disorders including dementias, cardiovascular disease, atherosclerosis, obesity, and diabetes. Age is also associated with cognitive decline particularly in cognitive domains associated with memory and processing speed. With increasing life expectancies in many countries, the number of people experiencing age-associated cognitive impairment is increasing and therefore from both economic and social terms the amelioration or slowing of cognitive aging is an important target for future research. However, the biological causes of age associated cognitive decline are not yet, well understood. In the current review, we outline the role of inflammation in cognitive aging and describe the role of several inflammatory processes, including inflamm-aging, vascular inflammation, and neuroinflammation which have both direct effect on brain function and indirect effects on brain function via changes in cardiovascular function.

Arterial stiffness and white matter integrity in the elderly: A diffusion tensor and magnetization transfer imaging study

BACKGROUND AND PURPOSE

The stiffness of large arteries and increased pulsatility can have an impact on the brain white matter (WM) microstructure, however those mechanisms are still poorly understood. The aim of this study was to investigate the association between central artery stiffness, axonal and myelin integrity in 54 cognitively unimpaired elderly subjects (65-75 years old).

METHODS

The neuronal fiber integrity of brain WM was assessed using diffusion tensor metrics and magnetization transfer imaging as measures of axonal organization (Fractional anisotropy, Radial diffusivity) and state of myelination (Myelin volume fraction). Central artery stiffness was measured by carotid-femoral pulse wave velocity (cfPWV). Statistical analyses included 4 regions (the corpus callosum, the internal capsule, the corona radiata and the superior longitudinal fasciculus) which have been previously denoted as vulnerable to increased central artery stiffness.

RESULTS

cfPWV was significantly associated with fractional anisotropy and radial diffusivity (p < 0.05, corrected for multiple comparisons) but not with myelin volume fraction. Findings from this study also show that improved executive function performance correlates with Fractional anisotropy positively (p < 0.05 corrected) as well as with myelin volume fraction and radial diffusivity negatively (p < 0.05 corrected).

CONCLUSIONS

These findings suggest that arterial stiffness is associated with axon degeneration rather than demyelination. Controlling arterial stiffness may play a role in maintaining the health of WM axons in the aging brain.

Regional Cerebrovascular Reactivity and Cognitive Performance in Healthy Aging

Cerebrovascular reactivity (CVR) reflects the response of brain blood vessels to vasoactive stimuli, such as neural activity. The current research assessed age-related changes in regional CVR to 5% CO2 inhalation in younger (n = 30, range: 21-45 years) and older (n = 29, range: 55-75 years) adults, and the contribution of regional CVR to cognitive performance using blood-oxygen-level dependent contrast imaging (BOLD) functional magnetic resonance imaging (fMRI) at 3T field strength. CVR was measured by inducing hypercapnia using a block-design paradigm under physiological monitoring. Memory and attention were assessed with a comprehensive computerized aging battery. MRI data analysis was conducted using MATLAB® and SPM12. Memory and attention performance was positively associated with CVR in the temporal cortices. Temporal lobe CVR influenced memory performance independently of age, gender, and education level. When analyzing age groups separately, CVR in the hippocampus contributed significantly to memory score in the older group and was also related to subjective memory complaints. No associations between CVR and cognition were observed in younger adults. Vascular responsiveness in the brain has consequences for cognition in cognitively healthy people. These findings may inform other areas of research concerned with vaso-protective approaches for prevention or treatment of neurocognitive decline.

Peak exercise stroke volume effects on cognitive impairment in community-dwelling people with preserved ejection fraction

AIMS

The association of vascular dysfunction and amyloid beta deposition attracted attentions for its relationship with cognitive decline. Previous studies show the correlation between the declined cardiac function and the cognitive impairment. In the present study, we analysed the association between cognitive functions and cardiac parameters in community-dwelling people with preserved ejection fraction without heart failure.

METHODS AND RESULTS

Subjects were 108 Japanese community-dwelling middle-aged and older adults with preserved ejection fraction (25 men and 83 women; mean age 74.7 years). Cardiac functional parameters at rest were assessed with B-type natriuretic peptide and echocardiography. The cardiopulmonary exercise test was used to test these parameters during exercise. Cognitive function was assessed with the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Other indices were assessed biochemically, physiologically, and physically. There were significant correlations between MoCA-J score and age (r = -0.388), peak oxygen uptake (VO₂ , r = 0.201), peak VO₂ /heart rate (HR, r = 0.243), peak VO₂ /weight (r = 0.244), peak metabolic equivalents (r = 0.244), usual walking speed (r = -0.200), and the Timed Up and Go test (r = -0.230). Multiple linear regression analysis showed peak VO₂ /HR was an independent determinant of MoCA-J score after adjusting for potential confounders (B = 0.424). After 6 months of exercise training with 64 subjects, we found that the per cent change of peak VO₂ /HR was related to the per cent change of MoCA-J score (r = 0.296).

CONCLUSIONS

These results suggested that peak VO₂ /HR (an index of stroke volume at peak exercise) might be associated with cognitive impairment based on the vascular cascade hypothesis.